make compressed .swf parsing possible,
link core php with -lz for getimagesize()
see also http://bugs.php.net/bug.php?id=29611

--- php-8.0.0rc1/ext/standard/image.c~	2020-10-09 18:50:01.000000000 +0300
+++ php-8.0.0rc1/ext/standard/image.c	2020-10-09 18:53:44.278879164 +0300
@@ -31,7 +31,7 @@
 #endif
 #include "php_image.h"
 
-#if HAVE_ZLIB && !defined(COMPILE_DL_ZLIB)
+#if HAVE_ZLIB
 #include "zlib.h"
 #endif
 
@@ -80,7 +80,7 @@
 	REGISTER_LONG_CONSTANT("IMAGETYPE_JP2",     IMAGE_FILETYPE_JP2,     CONST_CS | CONST_PERSISTENT);
 	REGISTER_LONG_CONSTANT("IMAGETYPE_JPX",     IMAGE_FILETYPE_JPX,     CONST_CS | CONST_PERSISTENT);
 	REGISTER_LONG_CONSTANT("IMAGETYPE_JB2",     IMAGE_FILETYPE_JB2,     CONST_CS | CONST_PERSISTENT);
-#if HAVE_ZLIB && !defined(COMPILE_DL_ZLIB)
+#if HAVE_ZLIB
 	REGISTER_LONG_CONSTANT("IMAGETYPE_SWC",     IMAGE_FILETYPE_SWC,     CONST_CS | CONST_PERSISTENT);
 #endif
 	REGISTER_LONG_CONSTANT("IMAGETYPE_IFF",     IMAGE_FILETYPE_IFF,     CONST_CS | CONST_PERSISTENT);
@@ -186,7 +186,7 @@
 }
 /* }}} */
 
-#if HAVE_ZLIB && !defined(COMPILE_DL_ZLIB)
+#if HAVE_ZLIB
 /* {{{ php_handle_swc */
 static struct gfxinfo *php_handle_swc(php_stream * stream)
 {
@@ -1321,7 +1321,7 @@
 			result = php_handle_swf(stream);
 			break;
 		case IMAGE_FILETYPE_SWC:
-#if HAVE_ZLIB && !defined(COMPILE_DL_ZLIB)
+#if HAVE_ZLIB
 			result = php_handle_swc(stream);
 #else
 			php_error_docref(NULL, E_NOTICE, "The image is a compressed SWF file, but you do not have a static version of the zlib extension enabled");